Abstract: Real-time monitoring and investigation showed that Sclerotinia stem rot of mechanical direct seeding rape occurred earlier than common sort. Disease severity rose with the rape developed, and more quickly during the early stage of anthesis, flower withering period and early silique mature period. Yield loss rate increased with the ill stem rate and disease index enhanced. Yield loss rate(Y1) correlated with ill stem rate(X1), as well as disease index(X2), all reached a highly significant level with related model Y1=0.5443302X1-2.3161(n=14,r=0.9860**), Y1=0.673408 X2-1.0164(n=14,r=0.9772**). Disease control index of mechanical direct seeding rape was ill stem rate as 11.8% and disease index as 7.6 when controlled once, respectively, and ill stem rate as 16.8% and disease index as 11.7 when controlled twice.

Key words: mechanical direct seeding, Sclerotinia sclerotiorum, yield loss rate, disease index, control inde